Tiller, who performed late-term abortions, already had been a victim of violence. As some anti-abortion websites hail the doctor's death, anti-abortion leaders decry the shooting.

LOS ANGELES AND WICHITA, KAN. — For years, abortion foes tried to put Dr. George Tiller out of business. One of the few American physicians who performed late-term abortions, he was targeted by violent extremists as well as principled opponents.

In 1986, his clinic was bombed. In 1991, it was blockaded for six weeks. In 1993, he was shot in both arms. In March, Kansas prosecutors tried him on charges of breaking an abortion law; he was acquitted. In May, vandals cut wires to security cameras and made holes in the roof of Tiller's clinic, Women's Health Care Services, a fortified single-story building where abortion foes keep daily vigil.

Until Sunday, when a gunman shot Tiller to death in the foyer of his church, the doctor had always overcome the daunting legal and physical challenges of his work, terminating pregnancies of women and girls who were in the 22nd week of gestation or beyond. But where supporters of legal abortion saw a savior, opponents saw a heartless killer.

Tiller was working as an usher at Reformation Lutheran Church and his wife, Jeanne, was in the choir when he was gunned down about 10 a.m.

Adam Watkins, 20, told the Associated Press that he was sitting in the middle of the congregation when he heard a small pop.

"We just thought a child had come in with a balloon and it had popped," he said.

Another usher told the congregation to remain seated, then escorted Tiller's wife out. "When she got to the back doors, we heard her scream, and so we knew something bad had happened," Watkins said.

Tiller's lawyers released a statement from Tiller's wife, four children and 10 grandchildren: "Today we mourn the loss of our husband, father and grandfather," it said. "This is particularly heart-wrenching because George was shot down in his house of worship, a place of peace."

Hours later, Wichita police announced they had arrested a 51-year-old man about 170 miles away. A Johnson County sheriff's spokesman said Scott Roeder was arrested near Kansas City, the Associated Press reported.

Wichita police said the suspect could be charged today with murder and aggravated assault.

U.S. Atty. Gen. Eric H. Holder Jr. said the Justice Department was involved in the investigation. In a statement, Holder pledged to help protect abortion facilities and providers around the country to prevent "related acts of violence."

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Obama 'outraged'

Tiller's slaying comes as President Obama, who supports abortion rights, has called for the opposing sides to find common ground. "I am shocked and outraged by the murder of Dr. George Tiller as he attended church services this morning," Obama said in a statement. "However profound our differences as Americans over difficult issues such as abortion, they cannot be resolved by heinous acts of violence."

Last month, in a commencement speech at the University of Notre Dame, the president issued a plea for respectful discourse, but acknowledged, "The fact is that at some level, the views of the two camps are irreconcilable."

Kelli Conlin, president of NARAL Pro-Choice New York, echoed that sentiment Sunday: "It is cold-blooded, vicious actions like today's assassination that make it hard for those of us in the pro-choice community to find common ground with those on the other side."

Some people on antiabortion websites hailed the slaying, the first killing of an abortion provider in the U.S. since Dr. Barnett Slepian was killed by a sniper at his home in Amherst, N.Y., in 1998. But the movement's leaders condemned it.

"It's tragic," said the Rev. Patrick Mahoney of the Christian Defense Coalition, who attended Tiller's trial in March. "The probability is that someone who opposed abortion did this. The reason we are pro-life is because we hate violence on any level. I don't know of one legitimate pro-life leader who would not unequivocally condemn this."

Mahoney said he had scheduled a news conference with antiabortion groups this morning on the steps of the Supreme Court to condemn the killing.

"One of my main concerns here is that the Obama administration and Democratic leaders don't make the same mistake that the Clinton administration made, and don't use this isolated episode to demonize an entire movement and try to take this tragedy for political gain," Mahoney said.

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Revival of sorts

Troy Newman, the head of the antiabortion group Operation Rescue -- who moved to Kansas from California to try to put Tiller out of business -- said he was "shocked, horrified and numb."

"It's a horrible day," Newman said. "Nobody wants anything to end like this. We want to bring abortionists to justice through the proper channels, through legal means. We know that Mr. Tiller was violating the law and we could prove it, and I am confident that we were a couple months away from getting his license revoked."

Newman was referring to an investigation of Tiller by the Kansas State Board of Healing Arts, which announced its 11-count administrative case against the doctor on the day he was acquitted.